Protective switch box



PROTECTIVE SWITCH BOX Filed July 29, 1924 I Urli PHJ l y a 2i* L "4 .Il jfl 5 18 :2 'lf IJ- I 4 Ih 5 6 2l/, zz /f9 zo l 4 31400/11150@ maf/MMM xhis @Howe/13 Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE PROTECTIVE SWITCH BOX Application filed July 29,

The invention is a protective switch box so constructed that when the switch is closed, access to fuses cannot be had, but opening of the switch permits the uncovering of an opening in the cover of the box opposite the fuses. The cover of my box is provided with a sliding shutter adapted to come over said opening. My switch lever is so formed and disposed, that a part of it comes in the way of pulling out the shutter and uncovering the opening when theswitch is closed.

In my preferred form the switch lever is formed with an offset or crank portion adapted to open and close the switch and .at the same time adapted to prevent opening the shutter when the switch is closed. Another feature of my device is that the circuit may be o cned from outside the box without necessarily uncovering the opening in the cover as is the casein many previous devices. Furthermore, when my shutter is out, exposing the fuses, itis not possible to close the switch.

This invention is a modified form of that shown in my co-pending application Serial #722,288 filed June 25, 1924.

The above and other objects and advantages will become apparent upon a study of the description and drawings in which Fig. 1 is a front elevation of my switch-box with the fuse shutter open, Fig. 2 is a section through the box taken along the line 2-2 of Fig. 1 and Fig. 3 is a section through the box taken along the line 3-3 of Fig. 1.

The switch box consists of two main pori tions, preferably of sheet meta-l, the body portion 4, and hinged cover 5, the hinges being shown at 6. Cover is provided with flanges which come over the walls of body portion 4 when 4cover 5 is closed. A tongue 7 is cut in 'cover 5 opposite hole 8 punched through the flange of cover 5 and the wall of body portion 4, through which the shackle of a lock or seal (not shown) can be passed for locklng cover 5 to the body portion 4.

Body portion 4 carries mounted upon it a porcelain fuse block 9 carrying the usual fuse contacts consisting of fuse sockets 10 and contact screws, one of which is shown at 11, pro- .vided in the center of each socket. Only the right hand socket (Fig. 1) is shown with a 1924. Serial No. 728,919.

fuse 28 in place, it being understood, of course, that a fuse 28 is to be provided for each socket 10. Leads (not shown) are adapted to be brought into the boX and connected to binding screws 12. A number of knock-out spots as at 13 are provided in various places in body portion 4, for conveniently bringing the leads into the boX.

Insulating switch block 14 is mounted upon body portion 4 adjacent to fuse block 9. Switch block 14 carries mounted upon it switch clips 15 and 16. Each of clips 15 is adapted to be electrically connected to a binding screw 17 on fuss block 9. Binding screws 17 by means well known to the art are electrically connected to fuse sockets 10, while contact screws 11 are electrically connected to binding screws 12. As is well known, when fuse plugs 28 are screwed into sockets 10, the circuit is closed between each pair of binding screws 12 and 17.

The circuit between each pair of switch clips 15 and 16 is adapted to be closed by contact arms 18 pivotally mounted at one end in switch clips 16. The other ends of contact arms 18 are held by an insulating cylindrical block 19 fastened by means of clip 2O to switch lever 21. Contact arms 18 are insulated from each other and from switch lever 21 by means of block 19. Leads (not shown) are adapted to enter the box and connect with switch clips 16. Vith the fuse plugs in place in sockets 10, when contact arms 18 are brought between the arms of switch clips 15, the circuit is closed between corresponding binding screws 12 and switch clips 16.

Cover 5 has fastened to its inside face, guides 22 spaced sufficiently apart to permit shutter 23 to slide between them. A handle 24 is provided on shutter 23 for sliding same back and forth to cover and expose opening 25 in cover 5. Handle 24 also serves as a stop to prevent shutter 23 from being pulled entirely away from cover 5 when said cover is unsealed and open, and it also limits the upward motion of said shutter.

Switch lever 21 is rotatably mounted in the walls of body portion 4 with its bearings in said walls on a line with the pivots of contact arms 18 in switch clips 16. The portion tion 4. This crank form of switch lever 21 Y enables it to throw contact arms 18 into and out of connection with switch clips 16 and also to prevent the opening of shutter 23 when the switch is in closed position. The

dot and vdash lines shown in Figs. 1 and 2,V

for switch lever 21 indicate its position when the switch is closed.

Shutter 23 has fastened to its inner face a lug 27. vVith the switch open, shutter 23 can be slid to expose opening 25 without interference between lug 27 and the crank portion of switch lever 21. `With shutter 23 open and the switch open, lug 27 is in its lower position (Figs. 1 and 2). In attempting now to close the switch, the crank portion of switch lever 21V would be stopped by the lower'or forward face of lug 27. With shutter 23 closed, lug 27 is in the position shown by the dot and dash lines in Figs. 1 and 2. Tn this position of the shutter, the switch can be opened and closed at will wit-hout any interference between switch lever 21 and lug` 27. However, with the switch closed, the crank portion of switch lever 21 shown in the dot and dashed position will prevent lug 27 and with itshutter 23 from being moved down so as to expose opening 25.

lVith the switch closed (Figure 2), crank member 21 (dotted position) is in such angular position that a fairly large force must be applied to slide the shutter before being able to open it. This is due to the fact thatV the point of contact or the part of the forward face of lug 22 which is in abutment with crank member 21, is but moderately offset from the axis of rotation of said member the offset considered being in a direction at right angles to 'the line of motion of the shutter. In other words, what amounts to a toggle holding action is obtained. The angular position shown for crank member 21 in the drawing, when the switch and shutter are open, does not produce such a great toggle holding effect as with the switch closed. ,Vhilc considerable force will be required to close the switch, without first independently lifting shutter 23 to'closed position, nevertheless when this force is used, the closing of the switch will also cause the shut-ter to be closed along with it.

its interior, ashutter, slidably mounted on said box for covering said opening, movable to close and expose said opening, and a rotatable switch lever having a crank member within said box, said crank member adapted to open and close said switch independently of movement of said shutter when the shutter is closed, said shutter having a projection inward of the box, the forward edge of said projection adapted to abut against said crank member when the switch is in closed position, said crank member being inclined sufficiently toward said edge when the switch is closed substantially to maintain said shutter in closed position.

2. A box, a switch mounted in the box, said box having an opening to provide access to its interior, a shutter slidably mounted on said box for covering said opening, movable to close and expose said opening, and a rotatable switch lever Vhaving a crank member within said box, said crank member adapted to open and close said switch independently of movement of said shutter when the shutter is closed, said'shutter having a projection inward of the box, the forward edge of said projection, adapted to abut against said crank member when the switch is in closed position, said crank member being pointed toward said edge and said edge suitably faced toward the axis of rotation of said crank member whereby movement of the shutter towards open position induces pressure on the crank member towards its axis of rotationsuicient to maintain said shutter in closed position.

` 3. A box, a switch mounted inthe box, said box having an opening to provide access to its interior, a shutter slidably mountedV on said box for covering said opening, movable to close and expose said opening, and a rotatable switch lever having a crank member within said box, saidcrank member adapted to open and close said'switch independently Y of movement of said shutter when the shutter is closed, said shutter having a projection inward therefrom, the forward face of said projection having a part adapted to abut against the crank member when the switch is closed,'the offset of the place of abutment to the axis of rotation of the crank member measured at right angles to the direction of motion of said projection being sufficiently small substantially to maintain said shutter in closedV position when the switch is closed, the forward face' of said projection adapted also to abut against said crank member when the switch is open, whereby the switch cannot be closed without closing thev shutter.

ALBERT EDGAR BLACKMAN. 

